苏北运东水网区浮游植物群落结构特征及与环境因子关系

为研究苏北运东水网区浮游植物群落结构特征及其与环境因子之间的关系，于2016年3月至12月对苏北运东水网区19个采样点进行了季节性浮游植物群落调查和水质监测。结果表明，浮游植物共计鉴定出142种，隶属于7门、75属，以绿藻门和硅藻门的种类数偏多，其中绿藻门共29属、58种，硅藻门共22属、44种。春、冬季以硅藻门密度最大，分别为2.49×106个/L和 1.67×106个/L；夏、秋季以绿藻门密度最大，为1.57×106个/L和 1.34×106个/L；Margalef丰富度指数（R）、Shannon-Wiener多样性指数（H''）、Simpson多样性指数（D）和Pielou均匀度指数（J）均在夏季最大，分别为1.374、3.198、0.944和0.831，在冬季和春季相对较小；运东河网区内部水流变缓，河网外部水体流动性相对较好，浮游植物密度的监测结果显示，内部河流大于外部河流，但生物多样性指数为外部河流小于内部河流；运东片各季节的主要浮游植物优势物种共有20种，春、冬季主要为硅藻门和隐藻门，而夏、秋季则主要为绿藻门和硅藻门，其中梅尼小环藻（Cyclotella meneghiniana）、尖针杆藻（Synedra acus）和啮蚀隐藻（Cryptomonas erosa）为全年常有的优势种。藻类优势物种与环境因子的CCA分析表明，影响运东片四季浮游植物群落分布的环境影响因子存在差异，其中BOD5、TP、NH3-N和CODMn是关键的环境影响因子。

Phytoplankton Community Structure and Its Relationship with Environment Factors in the Yundong River Network of Northern Jiangsu

The hydrological conditions and hydroecological processes are complex in the Yundong river network of Northern Jiangsu. The system is influenced by variations in season and discharge and also by operation of artificial control structures. In this study, a seasonal field investigation of phytoplankton and water quality parameters was carried out at 19 sampling sites in the river network of northeastern Jiangsu Province, from March 2016 to December 2016. The structure and spatial distribution of the phytoplankton community and their relationship with water quality parameters were analyzed based on the results. The study is significant for better understanding the structure and function of the aquatic ecosystem investigated and promotes protection and improvement of water quality. The study area, east of the Beijing-Hangzhou Grand Canal and west of Sanyang River, was well covered. A total of 142 phytoplankton species from 75 genera and 7 phyla were identified, with dominance by Chlorophyta (58 species, 29 genera) and Bacillariophyta (44 species, 22 genera). In spring and winter, Bacillariophyta densities were highest, with respective total densities of 2.49×106 cells/L and 1.67×106 cells/L. In summer and autumn, Chlorophyta densities were highest, with respective total densities of 1.57×106 cells/L and 1.34×106 cells/L. Margalef richness index (R), Shannon-Wiener diversity index (H''), Simpson diversity index (D) and the Pielou evenness index (J) were highest in summer, with respective values of 1.374, 3.198, 0.944 and 0.831. The indices were relatively low in winter and spring. Water flowed slowly in the inner Yundong river network and more rapidly in outer parts of the network. Phytoplankton density was higher in the inner area, but biodiversity was higher in the outer area. Twenty dominant phytoplankton species were detected in the study area. Bacillariophyta and Cryptophyta species dominated in spring and winter, and Chlorophyta and Bacillariophyta species dominated in summer and autumn. Cyclotella meneghiniana, Synedra acus and Cryptomonas erosa were dominant throughout the year. Canonical correspondence analysis (CCA) of the dominant species with environmental factors showed that the environmental factors affecting the phytoplankton community varied with season. However, biochemical oxygen demand (BOD5), total phosphorous (TP), ammonia nitrogen (NH3-N) and chemical oxygen demand (CODMn) were the primary factors affecting phytoplankton community structure.